A network alert has been sent out notifying everyone of the v1.1 mandatory update. If you're seeing it on your local wallet, it is intentional and was sent by us. If you've already upgraded to version 1.1, you have nothing to worry about. The alert will expire in 4 days
Getting this error while compiling:

configure: error: No working boost sleep implementation found. If on ubuntu 13.10 with libboost1.54-all-dev remove libboost.1.54-all-dev and use libboost1.53-all-dev
On what OS and what version of the source code (master or v1.1 ?)
I upgraded the new wallet (1.1) but it still says i need to upgrade
It is not a smart alert - it goes to the whole network. Just ignore it

Yea, looking back, we /maybe/ could've made it so that it only went to v1.0 clients, but we didn't make the proper preparation for it in v1.1. Basically, we would've had to bump the "protocol version number", which can change behavior and we'd have had to do more testing than we did to ensure that things still worked as expected.